|Figure 1: The ratio between the mass of the dust and the IRAS luminosity as a function of and the IRAS luminosity at different wavelengths|
Figure 2 shows that comparable amounts of dust and ionized gas are found in the central region of these galaxies. The total mass for these two components are in the range for the observed sample. This correlation is not produced by the distance effect mentioned earlier, as it shows up with the same strength in a flux-flux diagram.
The causal relationship between the dust content and the current stellar population of the galaxy sample can be inferred from the absence (Goudfrooij & de Jong 1995; Forbes 1991) or presence of a correlation between the dust mass and the blue luminosity of elliptical galaxies. We investigated this relationship (Fig. 3) and plotted the logarithm of the ratio of the dust mass to the blue luminosity as a function of the total blue luminosity and also as a function of the blue luminosity computed inside the emitting region (Table 5 of Paper I). Both plots suggest a correlation between the dust mass and the galaxy blue stellar population, which disagrees with the results of Goudfrooij & de Jong (1995).
|Figure 3: The mass of the dust normalized by the corresponding blue luminosity is plotted as a function of the blue luminosity measured inside the emitting region (upper panel) and the total blue luminosity of the galaxy (lower panel)|
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